Maximum demand meter reset mechanism



1950 J. R. MACINTYRE ET AL 2,497,578

MAXIMUM DEMAND METER RESET MECIANSM Filed Feb. 10, 1948 nventors John Fi. Mac:intgre Robert L..Davi&, bB /fl/V W6 T hei T Attorney Patented Feb. 14, 1950 UNITED STATES PATENT OFFICE MAXIMUM DEMAND METER RESET MECHNISM Application February 10, 1943, Serial No. 7,438

5 Claims.

Our invention relates to maximum demand meters of the biock interval type and in particular to the reset timing mechanism thereof, and its object is to provide a relatively simple, reliable, long-1H9 reset timing mechanism which performs its resetting operation accurateiy and quiokiy. In carrying our invention into eiect, we employ Geneva gearing for the dual purpose of dotermining the timing intervai and setting the pointer pusher t zero. This provides a positive drive through the reset mechanism without the use of an energy storage spring or its equivaient, and resuits in a low average load and a long life for the timing motgr. Also no energy is taken from the meter for resetting operations.

The features of our invention which are be lieved to be novei and patentabie wii1 be pointed out in the claims appended hereto. For a better understanding of our invention reference is made in the foilowing description to the accompanying drawing showing a perspective, expi0ded view of watthour demand meter mechanism to which our invention has been applied.

Referring to the drawing, I may be taken to represent the rotor disk of an induction watthour meter. This meter drives a kilowatt-hour register at 2 through gears at 3, 4, 5 and 6 to register the total kilowatts consumed by the meter.

Below register 2 is a maximum demand pointer 1 which registers the maximum watthour consumption of meter l on a scale 8 during predetermined time intervais such, for example, as fifteen minutes or one-half hour. In describing our invention, We will assume a 60-minute demand interval. This pointer is reset t0 a zero position generally at the end of each month after the maximum demand reading has been recorded by a meter reader. Beneath the maximum demand pointer and scale is an accumuiative demand register 9 on which a summation of the maxmium demand readings is registered. The register 9 is advanced Oni When the maximum demand pointer 1 is reset to zero. An accumulative demand meter of this general character is described and claimed in United States Patent No. 2,006,321June 25, 1935.

Shown at the upper right of the drawing is a timer motor li! which may be an alternating current synohronous motor of the type used for driving clocks. This motor is used in establishing the demand measuring timing intervai, and in performing the 60-minute intervai resetting operation, and also is used for resetting the maximum demand pointer 1 and adding its reading to the accumuiative register 9 at the end of the month. The monthiy resetting operation is per iormed through gear train H, 12, i3, M, and the (BD-minute interval period is estabiished and the 6Gminute intervai resetting operation 15 performed through a multiple unit Geneva gear train Hi, Hi, ii, i8, and gears at 19 and 26 interconnecting the Geneva gears with the motor and with each other.

demand meter dog part which is reset t0 a zero position every sixty minutes is represented as comprising a disk 22! having a pin 22 therein and an adjustabie screw 23 threaded through pin 22. This part is advanced in a clockwise direction by the meter through gearing at 24 and 25 and a friction clutch et 26 in accordance With the demand te ne measured. It is reset to zero in a oounterclockwise direction by motor H] through the Geneva gear timing intervai mecha nisn1 which includes a disk 21 having a pin 28 therein which actuates a gear sector lever 29 meshing With a gear 30 on the shaft oi dog 2l. When the dog pin 23 is advanced by the meter, it may engage and drive a cooperating dog arm 3i fixed on the shaft 32. Shaft 32 is in driving relation with demand pointer i through the gears at 33 and and hollow shaft 35. The maximum demand pointer a, its driving arm 3l, dog 2l, and the connected gear sector 29 of the reset mechanism are shown in approximateiy what may be considered the one half full scale position with pin 23 in driving contact with arm 3l The zero or reset position of dog disk 2! is With its pin 22 rotated counterolockwise from the position shown against an adjustaole zero stop 36. This resetting operation is accomplished by the rotation of disk 2i oounterclockwise during a one-iourth revoiution movement from approximateiy the position shown. During such movement pin 28 engages the taii of gear sector lever 29 and moves it up and to the right. The lever rotates clockwise about its pivot at 31, and its gear sector rotates gear 30 and the dog to zero position as pin 28 clears and moveg by the taii of lever 29. While the zero reset parts are positiveiy reset quickly, there is nothing resemb1ing a hammer- 1010W eiect that would cause rebound to errer. The parts arrive at the zero position While decelerating because the taii of the lever 29 which is eontacted by pin 28 is sioped off and the lever is otherwise shaped and pivoted to provide a precision zero setting without shock.

During any suoh resetting action a cam at 38 on a disk 351 engages a lever dl! pivoted at il and swings it to disengage the ciutch 26 between the meter and demand dog. Hence, the only load 1equred in moving lever 29 during a resetting operation is that necessary to overcome the friction of the part geared thereto When the clutoh 29 is open. This clutch is normally held olosed by a light spring '32 having an adjustable tensioning nut In practice the cam disl: 39 and pin disk 2? W111 generally comprise a single unitary part but are here shown as separate for clearness in the illustration.

Associated With each Geneva gear unit is a locking device for preventin rotation of the driven part except when advanced by the Geneva gear. Thus, on the shaft with Geneva gear sector as is a disk; Ml having.a CU.OU'SBCOT 45, and on the shaft with gear 56 is a locking gear 43. The raised periphara1 portion of disk 44 when adjacent locking gear 46 prevents rotation thereof but when the gear i6 is to be driven by sector 55, the cutout part l of disk 4 3 is adjacent locking gear 36 and allows it to rotate by giving clearance t a tooth therein. In the present illustration gear iis has eight teeth and gear t has four teetn, and these parts rotate one-fourth revolution each time sector I5 engages and drives gear i8.

Two Geneva gear units are represented. However, the number of these units and the driving ratios employed may vary with diiferent demand timing intervals, The second Geneva gear unit illustrated is similar to the one descrbed. In a Sil-minute demand interval mechanism the motor lE may have a terminal shaft speed of one revolution per minute and*use gearing at 19 so as to drive the parts 55, E9, i at two--thirds revo1uti0n per minute. Henoe, sector i5 W111 make one revolutsn every one and one-ha minutes. Sector l5 advances gear i9 two teeth or onefourtn revolution every one and oneha1f minutes and during approximately revo1ution of the driving part H), and hence, gear i% wili require six minutes for a complete revclution. An eighttoothed pinion at 29 meshes with a 20t00th gear which drives sector il. Hanse, gear sect0r il W111 require minutes to make a complete revoluti0n, and hence, will rotate the gear 4512 and disks 27 and 39 one-fourth revolution once every fifteen minutes. A150, sector H mtates in motion impulses or steps of onetenth revolution each, which is sufficient to completely drive gear la one-fourth revolution in one such step. The time duration of each such impulse is th same as the time duration during which gear id is advanced one-fourth revolution, or approximate ly l minutes=9 seconds. Moreover, the camming action between pin 28 and the tail oi lever 29 is such that a complete resetting action for a full sca1e maximum demand position of lever 29 will occur in somewhat less than revolution of disk r27. Hence, the actual demand interval resetting time is a maximum et nine seconds out 01" a 69minute interval, or onefourth of one per cent of the time.

This is important for two reascns: (l) IIigh accuracy in that the demand is being measured 99% per cent of the time and no energy is taken from the meter i for resetting purposes. (2) Low average Ioad on the timing motor. Thus, for 99% per cent of the time the ioad on motor corresponds to that necessary to drive the idle Geneva gear train; and the remaining time its load is comparable to that encountered in pr vious maximum demand meters where the motor furnishes the energy for resetting, usually by storing energy in a spring or weight. It is to be noted that during a resetting operation, clutch 26 is disengaged so that even then the actual motor load is not excessive. Hence, the motor and demand interval mechanismwill have small wear and a long life corresponding to the low load thereon.

The timing interval mechanism is fairly simple, may be made of simple rugged parts, and provides a direct drive to the reset dOg whi1e serving the purpose of a gear reduction and for establishing the timing interval. The mechanism is readily changed for difierent demand measuring periods. For example, adding another pin 28 and cam 38, degrees fr0m those shown, Will provide a 30-minute demand measurement interval, Provision is made for these extra attachments. Using a one to one gear ratio at 20 will provide a 2 l-minute interval mechanism. Eliminating the second Geneva gear unit and drivin disks 27 and. 39 from sector l5 will provide a sixminute demand interval mechanism etc. It is important that the number of motion impulses or advancing stepsof each Geneva gear which occurs during the demand period Seleoted be integers, and that one of such motion impulse advancing steps be sufficient to comp1etely operate the reset mechanism.

It is to be understood that the meter l advances the dog parts 2i during a 60-minute period, advancing the arm 3! and demand pointer 1 if they are not already advanced in proportion to the demand for such period. Then dog 2! is reset to zero while arm 3l remains where it is. During the next.period the operation is repeated and in case the demand is greater, demand pointer 7 is advanced further. These operations continue during a period Of a month and at the end of such month, pointer l indicates the maximum GO-minute demand that has occurred during such month. This is recorded, the demand pointer! and arm 31 are then resetto zero, and the maximum demandreadimg is added to the accumulauive demand register 9.

The apparatu5forrttfl1g the demand pointer 1 and adding its reading to register 9 is essentially the same as that described in Patent No; 2,006,321, but. Wil1b briefly reviewedhereim The gcar 47 is continuously driven by the.timer motor Il! through gearing I2, I3, gear 41 rotating in a clockwise direction. Normally, gear 41 is out of mesh With a gear 48. However, when the demand pointer E is to be reset, the knob 49 on the front of the dial is pushed inwardly by the meter reader. This. moves a shaft 50 endwise against a spring, not shown, and gear 48 with it a small amount so as to meshgear 48 with rotating gear d'2! This is the condition ofthe gears'as represented. Gear 48 now rotates in a counterclockwise direction, A pin .9 on its rear face engages and drives a pin 50 ongear 5l.- Gear 5l is in driving relation with demand pointer 1 through the gears at 33'and 34 and hol1ow shaft 35,*and has a position beiore being reset which corre sponds to the maximum demand 'measurememt. When knob 49 is pushed inward to intermesh gears l!- and 48', gear 48is rotative1y positioned so that a pair of stationary pins 52 and 52a are aligned with a pair of *slots of gear 48, one of whichisshown at 53-;- The pushing-in operation disengagestbese slotsand pins, a]1owing gear 48 to bedrivenandas soon asthe:slots 53 are out of alignment with the pins 52, the push button S may be released since the gear 48 Will be held in the pushed-back position by reason of the pins 52 and 52a riding on the face f gear 48 until the gear completes one revolution, since the diametrically opposite pins and s1ots are at diierent radii. When gear 48 has made one complote revolution, the pins again enter their slots and this resetting operation is complote. Gear 48 has a few of its gear teeth extended to the rear so as to mesh with gear M after the gear 48 has returned forward for the purpose of properly completing the operation before the gears run out of mesh.

When knob 48 is pushed to the rear, a friction clutch at 53 is engaged which places gear 5! in driving relation with a gear 54 which meshes With a gear 55 in driving relation with the totalizing register 9, so that this register is advanced by the same amount that gear 5| is reset in re turning the demand pointer 1 to zero position. This resetting operation ma also be performed manualiy by turning knob 59 counterclockwise by baud one complote revolution after being pushed inwardly. There is an overrunning clutch, not shown, in the drive train of motor which permits this. The resetting of demand pointer l either by motor l0 or manually a1so resets the l5minute interval dog parts at 2l to zero position, the clutch at 26 slipping for this purpose.

In the illustration the parts have been spread apart considerabiy and extra shaftng illustrated for the purpose of clarity. in actual practice the mechanism is made very much more compactly than the illustration Wonld indicate. For exampie, gears 2&3, la and 45 are a single unit and the tai1 of lever 29 engaged by pin 28 is shorter. Certain adjustments and refinements unnecessary for an understanding of the invention and its inclusion in the combination have been ornitted.

What We claim as new and desire to secure by Letters Patent of the United States is:

1. A demand mater comprising a demand meas uring part, means for advancing said part from a zero position in accordance With the demand to be measured, means for resetting said part t0 a zero position, a timer motor, and a plurality of Geneva gears in series driving relation between said motor and resetting means through which said resetting means and part periodically are directly driven to a zero position by said timer motor.

2. A demand meter comprising a demand measuring part, a meter for adVancing said part in accordance With the demand to be measured, a normaily engaged releasable clutch between said meter and demand measuring part through which said demand measuring part is advanced, means for releasing said clutch, means for resetting said part to a zero position, a timer motor, and Geneva gearing between said motor and the clutch releasing and part resetting means through which pericdicaily said clutch is released and said resetting means and part are driven directly by said motor to zero position while the clutch is released.

3. A demand meter comprising a demand measuring part, means for advancing said part from a zero position in accordance With the demand to me measured, means for resetting said part to a zero position, a timer motor, and a plurality of Geneva gears oonnected in series driving rela tien between said motor and resetting means for periodicaliy directly driving said resetting means and part to a zero position, said resetting operation 'being completed during a single motion impulse of all of said Geneva gears, the number of motion impulses made by each Geneva gear between resetting operations being integers.

4. A demand meter comprising a demand measuring part adapted to be advanced during a demand measuring time interval in accordance with the demand to be measured, a normally engaged releasable clutch through which said demand measuring part is advanced, means for releasing said clutch and means for resetting said demand measuring part to a zero position, a timer motor, two Geneva gear units in series driving relation between said motor and said clutch releasing and resetting means, the continuons rotary motion of the timer motor producing a considerable number of periodic forward motion driving impulses through the first Geneva gear unit and a lesser number of periodic forward motion driving impulses through the second Geneva gear unit during a demand measuring interval, said clutch releasing and resetting operations being completely performed by direct drive from said motor through said Geneva gears at the end of said demand measuring interval during one of said forward motion driving impulses.

5. In a demand meter, a reset mechanism, a constant speed timer motor and time interval establishing driving means between said motor and reset mechanism for directly operating the latter from the motor at the end of demand measuring time intervals established thereby, comprising a pair of similar Geneva gear units in series driving relation each having driving and driven parts, the driving parts rotating the driven parts onefourth revolution during approximateiy onetenth revolution of the driving part, the driving part of the first Geneva gear unit being driven by said motor at two-thirds revolution par minute, a 2:5 gear reduction between the driven part of the first Geneva gear and the driving part of the second Geneva gear whereby the driven part of the second Geneva gear is advanced one-fourth revo1ution every fifteen minutes during approximately a nine-second time interval, said resetting mechanism being completeiy operated by the driven part of the second Geneva gear during one such one-fourth revolution.

JOHN R. MACINTYRE. ROBERT L. DAVIS.

REFERENCES CITED UNITED STATES PATENTS Number Name Date 1,456,104

Hall May 22, 1923 

